Key Highlights

● Profusa traded at about $1.15 in an early-afternoon snapshot on October 22.

● The figure is an intraday snapshot rather than a confirmed close.

● An 8-K dated October 15 flagged potential dilution.

● An earlier 8-K dated October 9 disclosed a matter relating to the auditor.

Shares of Profusa (NASDAQ:PFSA) soared on Thursday, October 22, 2026, standing out as one of the biggest gainers on the Nasdaq Composite in a session dominated by a selloff in AI and chip stocks. The stock traded at about $1.15 in an early-afternoon snapshot of health care movers, having already climbed sharply in premarket trading.

The rally came without a company-specific announcement. Profusa did not issue a press release, earnings update or partnership news tied to the move.

Micro-cap stocks like Profusa can be highly volatile on thin news. With a small market value and a share price close to $1, even modest changes in buying interest can produce outsized swings, in either direction.

Recent filings in the background

While there was no fresh news on Thursday, Profusa's recent regulatory filings provide some background. According to company filings, an 8-K dated October 15 flagged potential dilution, and an earlier 8-K dated October 9 disclosed a matter relating to the company's auditor.

Neither filing was new on Thursday, and there is no indication that either was connected to the day's move. Dilution, which happens when a company issues new shares, typically weighs on a stock price because each existing share then represents a smaller slice of the business. Thursday's rally ran in the opposite direction.

Profusa is grouped among health care stocks. Like many small health care companies, its shares can be sensitive to shifts in sentiment.

A rough day for the Nasdaq

The gain came against a hostile backdrop for the index. The Nasdaq Composite closed at 26,008.86, down 694.00 points, its steepest drop since June 5. The decline ended a seven-session winning streak and wiped out about $1 trillion in market value, according to market data.

The selling was concentrated in AI and semiconductor stocks. Investors reacted to the heavy spending plans from Meta Platforms (NASDAQ:META), revealed after Wednesday's close, and to Lam Research (NASDAQ:LRCX)'s outlook, which flagged supply constraints. The Philadelphia Semiconductor Index posted its biggest one-day drop since June 23.

Under the surface, the picture was more mixed. About two of every three S&P 500 stocks rose, according to market reports, and the health care sector hit a record high. Consumer staples, utilities and financials also gained as investors rotated toward defensive areas. The Russell 2000 index of smaller companies edged up 3.01 points to 2,784.03.

On the Nasdaq itself, losers beat gainers. Market data counted 2,766 decliners against 2,022 advancers, with 342 new lows and only 82 new highs.

Why micro caps move without news

Stocks trading near $1 often attract short-term traders who scan for momentum. A sudden jump can draw more buyers, which pushes prices further before the move fades. Low share prices and limited liquidity mean a relatively small number of trades can move the stock a long way.

That also means gains can reverse just as quickly. Thursday's figure was an intraday snapshot rather than a confirmed closing level.

Profusa Is Watched for Filings and Follow-Through

Investors will watch for any filing or announcement from Profusa that might explain the move, and whether the gains hold into Friday's session. Market-wide, Friday brings S&P Global PMI data and the final University of Michigan sentiment reading. The Federal Reserve meets on October 27 and 28, with its decision due on Wednesday, October 28.